On IGTV, long-form vertical videos can go as long as
ten minutes (previously, Instagram videos were limited to one minute).
Instagram is making some exceptions for creators with massive audiences:
They can post up to 60 minutes of video. IGTV videos will all be
prerecorded, not live, although Instagram product manager Ashley Yuki
indicated that live video is something the company will be looking at in
the future.

Unlike
the main Instagram app, which shows video “Stories” as bubbles at the
top of the page and displays uploaded videos as part of the regular
feed, IGTV videos will appear as a series of rectangular thumbnails at
the bottom of a creator’s page. Once you tap on one, the video goes full
screen. On the lower left-hand corner of each video are the same three
icons you see now on Instagram: a heart, a comment bubble, and a share
tool. Tap on those for the same functionality as on the main Instagram
app.

If you ask which is best platform for YouTube creators, in 2018 YouTube is Best platform For creators but in future IGTV is biggest competitor to YouYube

Instagram has revealed it now has 1 billion users worldwide since it first launched in 2010.

It also announced plans to launch a new app, IGTV, designed to show longer videos of up to one hour.

The app will launch sometime in the next few weeks for Android and iOS and is meant to compete with YouTube.

From both a consumption and a content-creation perspective, IGTV is
going directly up against YouTube, which just announced it has more than
1.9 billion monthly logged-in users, and is already well established as
a place for creators to distribute long form video. Instagram hopes the
platform will be used by already-popular creators, like former Vine
star Lele Pons, who has more than 25 million Instagram followers
and who also appeared on stage at Wednesday’s event. The app is
launching with a group of pre-selected video stars, including publishers
like National Geographic, which has more than 88 million followers on Instagram, and brands like Benefit cosmetics. But it will be open to anyone who uses Instagram over the coming weeks.

Also like TV, IGTV has channels. But, in IGTV, the creators are the
channels. When you follow a creator on Instagram, their IGTV channel
will show up for you to watch. Anyone can be a creator — you can upload
your own IGTV videos in the app or on the web to start your own channel.